Geared screwdriver

ABSTRACT

A geared screwdriver having an improved mechanical advantage. The tool is provided with a gear train in driven connection with a screwdriver shank. The latter is disposed to turn within its handle. The gear train is housed in a structure which can be turned to operate the shank with the handle remaining fixed or, in the alternative, the latter may be turned to drive the shank with the housing fixed in place affording a different mechanical advantage from that which is afforded in the first mode of operation.

United States Patent 1191 Sheffield 1 July 16, 1974 GEARED SCREWDRIVER2,756,792 7/1956 Hirschman 145/50 R 145 66 [76] Inventor: George V.Sheffield, 133 Van Dyke 3580097 5/1971 van Dalen Rd., Hopewell, NJ.08525 1 Primary Exammer-Al Lawrence Sm1th Flledi P 1973 AssistantExaminer-J. T. Zatarga 211 Appl. No.: 354,779

[57] ABSTRACT [52] 145/ 50 81/5731 2 A geared screwdriver having animproved mechanical [51 i t Cl B25) 15/02 advantage. The tool isprovided with a gear train in d 61 L driven connection with ascrewdriver shank. The latter 1 0 /57 3 is disposed to turn within itshandle. The gear train is housed in a structure which can be turned tooperate 56 R f d the shank with the handle remaining fixed or, in the 1e erences alternative, the latter may be turned to drive the shankUNITED STATES PATENTS with the housing fixed in place affording adifferent 348,765 9/1886 Neal 145/50 R mechanical advantage from thatwhich is afforded in 1,493,160 5/1924 Pierce 145/66 the first mode ofoperation. 1,991,766 2/1935 Matveyeff 145/61 L 2,659,255 11/1953 Bates81/5731 X 1 Claim, 2 Drawing Figures screwdriver the shank of which isoperated through This invention relates to hand tools and, inparticular, to screwdrivers the shanks of which are driven through atrain of gears.

The present invention contemplates a screwdriver having a rotatableshank on the end of which a gear is mounted. The gear is one of a seriesof spur gears, the shank being driven by a pair of said spur gears onturning the housing for the gear train or, alternatively, by the entireseries of spur gears on turning the handle alone which is disposed aboutthe shank. The separate modes of operation afford a correspondingdifference in mechanical advantage.

One object of the invention is to provide an improved a gear train.

Other objects and advantages of the invention may be appreciated onreading the following detailed description of one of its embodimentswhich is taken in conjunction with the accompanying drawings, in which:

FIG. 1 is an exploded perspective view of the screwdriver; and

FIG. 2 is an enlarged section taken on the line 2-2 of FIG. 1.

Referring to the drawing, screwdriver shank 4 is removably connected bymeans of projection 6 to the end of shaft 8. Pinned to the shaft is gear10 in gear housing 12 having a cover 13. Disposed about the shankbetween the projection6 and the housing 12 is handle 14. The shaft isjournalled in internal sleeve 16 integral with the handle and in platemember 18 interiorally fixed to the housing 12. Mounted on the shaftproximate the handle is ring 20 which prevents the shaft from slidingaxially.

Spur gear 22 attached within the housing 12 to the end of the sleeve 16to turn about the shaft 8 is in engagement with gear 24 of largerdiameter. The latter is fixed on one .side of the member 18 to studshaft 26 journalled in the member 18. On the other side of the member 18is spur gear 28 mounted fixedly on the shaft 26. The gear 10 of largerdiameter than the gear 28 is in engagement therewith.

In operation, if the housing 12 is held in a fixed position and thehandle 14 is turned, the mechanism operates as an ordinary gear trainand there results a mechanical advantage represented by a quotientwherein the product of the diameter of gears 24 and 10 are divided bythe product of the diameters of the gears 22 and 28. On the other hand,if the handle 14 is held fixed and the housing 12 is turned, themechanism operates as a planetary gear train having a mechanicaladvantage represented by the product of the diameters of the gears 24and 10 divided by the product of the diameters of the gears 24 and 10less the product of the diameters of the gears 22 and 28.

Various modifications of the embodiment of invention as described abovemay be effected by persons skilled in the art without departing from anyprinciple of invention as defined in the appended claims.

What is claimed is:

l. A geared screwdriver comprising an output shaft and a screwdrivershank afixedly connected therewith,

' shaft being journalled insaid plate member, a stub shaft journalled insaid plate member, and a pair of spurgears in said gear train operativeas planetary gears fixedly mounted on said stub shaft respectively oneach side of the plate member, one of said spur gears engaging saidoutput gear, said gear train including athird gear engaging the other ofsaid spur gears, said third gear being connected to said sleeve andjournalled on said output shaft.

1. A geared screwdriveR comprising an output shaft and a screwdrivershank afixedly connected therewith, a handle, a gear fixedly mounted onsaid output shaft, a gear train and a sleeve connected to said handle,said sleeve being internally fixed to said handle and journalled on saidoutput shaft, said gear and gear train being disposed in a housing, aplate member partitioning the interior of said housing and afixedthereto, said shaft being journalled in said plate member, a stub shaftjournalled in said plate member, and a pair of spur gears in said geartrain operative as planetary gears fixedly mounted on said stub shaftrespectively on each side of the plate member, one of said spur gearsengaging said output gear, said gear train including a third gearengaging the other of said spur gears, said third gear being connectedto said sleeve and journalled on said output shaft.